Random variables can be classified into two main categories based on the possible values they can take on:
1. Discrete random variable: A random variable that can take on a countable number of distinct values. For example, the number of heads obtained when flipping a coin 3 times is a discrete random variable because it can only take on the values 0, 1, 2, or 3.
2. Continuous random variable: A random variable that can take on any value within a specified range or interval. For example, the time it takes for a computer to boot up is a continuous random variable because it can take on any value within a range of possible boot times.
Answer: Discrete random variable and Continuous random variable